Problem: Combine like terms to create an equivalent expression. $\dfrac17-3\left(\dfrac{3}{7}n-\dfrac{2}{7}\right)$
Solution: Use the distributive property to multiply the ${-3}$ into the parentheses. $\phantom=\dfrac17{-3}\left(\dfrac{3}{7}n-\dfrac{2}{7}\right)$ $=\dfrac17+({-3})\cdot\left(\dfrac37n\right)+({-3})\cdot\left(-\dfrac27\right)$ $=\dfrac17-\dfrac97n+\dfrac67$ $={\dfrac17}-\dfrac97n+{\dfrac67}$ $=-\dfrac97n+\dfrac77$ $=-\dfrac97n+1$ The expanded expression is $-\dfrac97n+1$